U.S. Pat. No. 4,733,269, Kasahara et al, issued Mar. 22, 1988; U.S. Pat. No. 4,796,054, Maeno et al, issued Jan. 3, 1989 and U.S. Pat. No. 4,872,037, Kasahara et al, issued Oct. 3, 1989 show image forming apparatus in which a series of single color toner images are formed on a photoconductive drum and are transferred in registration to a transfer surface associated with a transfer drum. For example, the transfer surface can be the outside surface of a receiving sheet carried by the transfer drum. The images are superposed in registration to form a multicolor image on the receiving sheet carried by the transfer drum. In each of these image forming apparatus the photoconductive drum and the transfer drum are permanent portions of the apparatus which allows them to be carefully mounted to maintain a precise transfer relation between the photoconductive drum and the receiving sheet carried by the transfer drum.
It is also known to create a series of toner images on an image member and to superpose them in registration on a transfer surface integral with a transfer member (rather than associated with it) to create a multicolor image on that surface. The multicolor image is then transferred to a receiving sheet in a single step at a position generally remote from the image member. See, for example, FIG. 8 of U.S. Pat. No. 4,712,906 to Bothner et al, issued Dec. 15, 1987.
U.S. Pat. No. 4,876,577, Ogura et al, issued Oct. 24, 1989, and U.S. Pat. No. 4,591,258 to Nishino et al, issued May 27, 1986, show image forming apparatus in which the image member is supplied to the apparatus in a replaceable cartridge. In each instance, the cartridge includes a charger, a cleaning device and an optical opening for exposing the image member to create electrostatic images. The images are toned either by apparatus inside the cartridge or outside the cartridge and the images are transferred to a receiving sheet that is fed into contact with the image member through an opening in the cartridge provided for that purpose. Apparatus using these cartridges produce monocolor images which are transferred to a surface of a receiving sheet which is held to the image member electrostatically, orientation between a transfer drum and the image member is not critical to the final image.
Many other references show such image member cartridges, and they are used commercially in personal copiers and laser printers. In general, the image member is a photoconductive drum and is driven by an end connection from a receiving apparatus to the drum through the end of the cartridge. Mounting of the cartridge in the image forming apparatus requires assuring that the drive connection is effectively made. To the best of applicant's knowledge, this type of image member cartridge has not been used in an image forming apparatus which forms multicolor images by superimposing single color toner images on a recirculated transfer surface.